Often, patients that are bedridden or immobile can develop decubitus ulcers (pressure sores or bedsores). Such ulcers are often caused by pressure, friction, shear forces, moisture, and/or heat. Pressure results in a reduction of blood flow to the soft tissues of the body, particularly the skin. Continuous lack of blood flow, and the resultant lack of oxygen, can cause the skin to die or atrophy, and cause ulcers or sores to form. Friction and shear of the skin against the support surface can lead to skin tears and decubitus ulcers. Moisture and heat may lead to skin maceration. Other factors play a part in determining the speed with which such ulcers will either tend to form or heal, including such as the overall health of the patient and such patient's nutritional status.
From a consumer user perspective (i.e., not necessarily involving long periods of bed rest beyond normal nighttime sleeping), moisture and heat buildup and other factors can create discomfort for the user.
To insure normal (or, at least, relatively improved) blood flow to such areas of potentially problematic contact, patients are often regularly turned or repositioned by medical personnel. Turning or repositioning of patients, however, is not always possible, particularly where trained medical staff is not available. Additionally, repositioning can be painful and disruptive for the patient.
In an effort to overcome such difficulties, a number of mattresses and related devices (such as mattress coverlets or toppers) have been developed with the intention of more evenly distributing, across the patient's skin, the pressure generated by the weight of the body. Some such devices make use of static supports such as foam, air or water mattresses, while others involve the use of alternating pressure inflatable features in order to dynamically shift the location of support under the patient. Two examples of support surfaces are illustrated in U.S. Pat. Nos. 5,509,155 and 5,926,884.
In addition to such approaches to efforts for redistribution of skin pressure, an additional feature has been utilized to help address other of the aforementioned factors important to the healing and/or prevention process. In particular, a low air loss feature has been used to aid in the removal of both moisture vapor and heat, thereby reducing both at the patient-bed boundary. Such features are done in an effort to prevent skin maceration, keep wounds dry, and promote healing. In a consumer user context, the features result in improved comfort during sleep or rest.
Various approaches have been practiced for achieving a low air loss support surface. For example, in some instances, relatively tiny holes can be provided in the top surface of inflatable air cells of an air mattress having a vapor-permeable top surface, to allow extra air to circulate inside the mattress to assist in drying moisture vapor otherwise passing through the top surface from the patient. In other exemplary configurations, relatively tiny holes can be provided in the top surface of the mattress so that air vented from air cells can transfer through the top surface to the patient in order to remove both heat and moisture from the area immediately surrounding the patient.
Per still further exemplary approaches, in some instances a multi-layer mattress coverlet can be used wherein the top layer is perforated to allow air flowing between the top layer and a middle vapor-permeable layer to exhaust across the patient, thus aiding in removing both moisture and heat from the area immediately surrounding the patient. For some such devices, one of the layers of such a multi-layer approach may be a three-dimensional fabric, which allows for additional moisture vapor to be carried away from the patient.
While each of these approaches is useful for its purpose, there are various disadvantages with these approaches and in particular, with using them individually. Some of the referenced approaches to obtaining a low air loss feature require a relatively large compressor pump or the like to maintain sufficient air to inflate the air cells of the mattress. Such large compressor pumps tend to be very noisy, require high electrical consumption, and themselves can generate significant heat in a relatively confined area. Such high electrical consumption, and the additional need for continuous blower operation, has, in the past, resulted in potential over-heating of the air used to circulate about the patient. Conversely, in the case of an elderly patient, airflow directly across their body could result in an uncomfortable reduction in body temperature or even a drying out of the skin beyond that which is helpful.
Additionally, having holes in air cells of an inflatable air system results in a support surface that will deflate if there is a loss of electrical power or if no such power supply is available. Further, having perforations in the patient-bed contact surface results in a mattress that is not fluid-proof. Such arrangement allows for potential contamination of the interior of such mattress by bodily fluids, products used to treat the patient, and/or products used to clean such mattress itself. Some exemplary approaches generally fail in some respects to allow air to flow under load (i.e., underneath the patient) or through the top surface to the patient's skin when supporting the weight of the patient.
Similarly, some prior art mattresses and mattress coverlets have had difficulty with billowing, which is generally an uncontrolled inflation of the upper surface of a mattress or mattress coverlet in the area immediately surrounding the outline of a patient's body when the patient lies on the mattress. In essence, the mattress or mattress coverlet fails to fully support a patient and instead seemingly envelops them when the patient's weight is applied thereto. Thus, such billowing further illustrates the failure of some prior mattresses and/or mattress coverlets to fully support the patient, therefore resulting in air flow through the mattress, mattress top layer, or through the coverlet and around the patient, rather than flowing underneath the patient to aid in controlling moisture and heat.
Various aspects of the prior art are described in the following exemplary-only issued U.S. patents. Stolpmann (U.S. Pat. No. 6,855,158) discloses in part a closed-loop control system for support surface temperature control, used in conjunction with a low air loss mattress. Harrison et al. (U.S. Pat. No. 6,859,967) discloses a mattress overlay and various air inflated bladders incorporating thermal control to regulate a patient's body temperature while also using pressure shifting techniques to reduce the risk of bed sore formation.
Gazes (U.S. Pat. No. 5,970,550) discloses a multiple compartment inflatable mattress which involves controlling the temperature of a circulated medium in order to control the mattress temperature. Stroh et al. (U.S. Pat. No. 5,168,589) discloses a pressure reduction air mattress (or alternatively an overlay) which uses adjustable air flow rates as well as heating elements for warming air passed therethrough or thereby. Heaton (U.S. Pat. No. 6,730,115) provides an inflatable mattress and related heat exchanger technology, intended in part for providing cooling contact for a person supported thereon, rather than heating, in order to provide cooling as part of a clinical treatment. Totton at al. (U.S. Pat. No. 6,782,574) relates to an air-powered low interface pressure support surface in which an air inflatable mattress and mattress coverlet are provided for the prevention and treatment of decubitus ulcers (i.e., pressure sores or bedsores).
Maier et al. (U.S. Pat. No. 6,223,369) is another example of a various prior art patient support surfaces which make use of integrated air support cylinders surrounded by foam patient support features and collectively encased in a cover. Such basic combination of features provide one example of a patient support mattress to which additional features and modified features may be practiced in accordance with the presently disclosed subject matter, as further discussed herein. As background, FIGS. 1 and 2 herewith are taken from such '369 patent, and illustrate background subject matter as follows.
FIG. 1 is a generally top and partial side perspective view, in partial cutaway, of an exemplary prior art patient support surface. FIG. 2 is a cross sectional representation, taken generally along a middle position of the illustration of FIG. 1, representing as such prior art embodiment in part would appear in assembled form.
FIG. 1 illustrates an exemplary patient support surface generally 10 showing an exemplary exterior fitted cover 12, which may comprise such as stretch fabrics. A pleated design may be practiced for full integration with shear-relieving surfaces of foam toppers contained therein, and turning handles (not shown) may be optionally provided.
FIG. 1 represents a perimeter bolster 14 as illustrated in dotted line, as enclosed within covering 12. Such bolster 14 may include a pair of opposing longitudinal elements 16 and 18 and an opposing pair of end rails or elements 20 and 22 integrally associated therewith. Preferably, perimeter bolster 14 may comprise resilient polyurethane materials with selected characteristics. The several components 16, 18, 20, and 22 thereof may be joined by gluing or the like, as well understood by those of ordinary skill in the art.
As further shown in partial cutaway in exemplary prior art FIG. 1, a foam topper generally 24 may be integrally included within patient support surface 10. Particularly the upper support surface of such foam topper may include a variety of constructions designed and intended to facilitate pressure relief. Pressure relief, for example, may be provided by a number of lateral cuts or channels generally 26 formed in such surface as illustrated in solid line. It is to be understood that a number of longitudinal cuts or channels may also optionally be provided (as represented generally by dotted lines 28) for improved shear-relief performance or other improved features. As will be well understood by those of ordinary skill in the art, the combination of lateral channels 26 and longitudinal channels or cuts 28 results in a plurality of separate upright support elements, the size and construction of which may vary over the surface of topper 24 so as to provide selected support characteristics. Examples of such various arrangements as may be practiced in combination with the subject matter are discussed throughout commonly owned U.S. Pat. Nos. 4,862,538; 5,025,519; 5,252,278; and 5,580,504, the complete disclosures of which are fully incorporated herein by reference.
FIG. 1 further represents in the partial cutaway exposure thereof the fact that foam topper 24 may be provided with particular underside features for accommodating and receiving an air cylinders). In particular, the end generally 30 of an exemplary longitudinal air cylinder is represented as positioned near one end of patient support surface 10. Different numbers and sizes of generally longitudinal air cylinders may be practiced, and laterally-positioned air cylinders may also be practiced with certain variations.
FIG. 2 represents the exemplary use of four longitudinal air cylinders 36, 38, 40, and 42. Each such air cylinder has a respective end, at which a connection is made with a respective section of air tubing, which interconnects with the interior of the respective air cylinders to facilitate initially establishing the air pressure therein and/or later adjusting such amount of air pressure.
Another aspect of the exemplary prior art embodiment represented in present FIG. 2 is the inclusion of a pair of inner bolsters 68 and 70, which run longitudinally along the lengthwise axis of a patient support surface. As illustrated, each inner bolster 68 and 70 has a respectively inwardly facing concave surface which interacts with part of the curvature of respective air cylinders 36 and 42. Still further, each concave face is provided with at least one respective curved slot 76 and 78, respectively. FIG. 2 further represents additional aspects of the exemplary prior art mattress, with a plurality of depending elements (not marked) which form downwardly facing arches which interact and interface with the generally top sides of the respective air cylinders 36, 38, 40, and 42. Such resulting combination cradles and surrounds the air cylinders, to provide an interlocked, integrated design.
The FIG. 2 cross section also shows the placement relationship among the air cylinders and various exemplary foam components. The locations of a foam topper, perimeter bolster components 16 and 18, and inner or side bolsters 68 and 70 are all distinguished by the use of differentiated cross hatching, as will be well understood by those of ordinary skill in the art. A general outward path of an exemplary air tube is represented in dotted line by air tube 64. Wide welds 96, 98, and 100 are created for holding together adjacently respective pairs of air cylinders. In general, the air cylinders are integrally formed so as to be reinforced, fabricated from, for example, high tinsel woven nylon fabric fused to heavy gauge polymeric film.
FIG. 2 represents an overall support strategy achieved with the illustrated structural arrangement, enhanced by selectively utilizing foam having different support characteristics. For example, in relation to each other, perimeter bolster 14 (only components 16 and 18 thereof are represented in FIG. 2 may be of relatively more dense material for relatively greater support than side or inner bolsters 68 and 70, which in turn may be of relatively greater density or firmer support than a foam topper portion. For specific examples, it will be understood by those of ordinary skill in the art that various nomenclatures may describe support characteristics of a given piece of foam. In this instance, ILD is intended to refer to the known characteristic of so-called indentation load deflection. Indentation load deflection (ILD) may be defined as the number of pounds of pressure needed to push a 50 square inch circular plate into a pad a given percentage deflection thereof. For example, a 25 percent ILD of 30 pounds would mean that 30 pounds of pressure is required to push a 50 square inch circular plate into a four inch pad a distance of one inch (i.e., 25 percent of the original, unloaded thickness).
Using a 25 percent ILD characteristic for description purposes, perimeter bolster 14 (including all elements 16, 18, 20, and 22 thereof) may in some instances comprise about a 54 pound ILD, while side or inner bolsters 68 and 70 may each comprise about a 50 pound ILD and while a foam topper feature may comprise about a 35 pound ILD. Other ILD characteristics in a range of from about 25 pounds to 60 pounds, or in some instances, outside of such range, may be practiced, as desired.
The disclosures of all of the foregoing U.S. patents are fully incorporated herein by reference, for all purposes.
While various implementations of therapeutic mattresses or mattress coverlets have been developed, no design has emerged that generally encompasses all of the desired characteristics as hereafter presented in accordance with the subject technology.